The present invention relates to a process and apparatus for forming a plastics laminate.
Plastics laminates are normally formed by the steps of heating, compressing and cooling while maintaining registration of the various layers of material forming the laminate. Such laminates are used, for example, to make printed circuit boards.
One known apparatus for forming laminates is the manual compression press where two heated platens are formed together by a hydraulic ram. The laminate materials are placed between the platens, then compressed and heated. The platens are then cooled to below some critical temperature so that the material will solidify and stiffen. This procedure is very slow, since it takes an appreciable time to heat up and then cool down the platens. This also causes appreciable energy losses.
Separate heating and cooling presses are sometimes used in the process. This saves time and energy, but is still relatively slow since any one laminate sample must be heated, or cured, for 30 minutes or more.
Another process involves the use of a tiered press, in which several laminate samples can be cured simultaneously. However there are mechanical difficulties in loading and unloading a relatively high stack from several layers simultaneously. Both the heating and cooling press will have several tiers, with complex systems for transfer from one press to another and elevator systems for loading and unloading. If the complex transfer mechanism fails at any stage, materials may be stuck between the presses, causing partial cure and the ruin of possibly thousands of dollars worth of material.